Adoptive immunotherapy approaches for cancer treatment are limited by the exhaustive activation protocols necessary for sufficient T cell expansion. The resultant tumor-specific CD8 cell population is in a hyporeactive state, characterized by reduced cytokine polyfunctionality, upregulation of inhibitory receptors, and decreased proliferative capacity. Less terminally differentiated cells - that is cells that still hve polyfunctionality and proliferative potential - have been linked to greater efficacy in clinical trals. The goal of the proposed project is to investigate the role of a novel target, sprouty2, in rescuin chronically activated CD8 cell effector functions in adoptive immunotherapy through the development of an innovative dual-acting artificial antigen presenting cell (aAPC). Sprouty2 (SPRY2) has been identified as a negative regulator of polyfunctionality in chronically activated HIV-specific CD8 cells, and its knockdown restores these effector functions. The engineered platform will function in two capabilities: 1) stimulate a single clone of tumor-targeting CD8 cell to attack and destroy cancer cells and 2) specifically knockdown an inhibitory molecule, SPRY2, in only these tumor-specific cells capable of interacting with the aAPC. The ability to knockdown SPRY2 expression in a monoclonal population of tumor-targeting CD8 cells may improve ACT efficacy while reducing or minimizing off-target effects associated with systemic immune activation. To accomplish these goals, the project will progress in three phases. First will be th synthesis and optimization of a dual-acting nano-aAPC. The aAPC will be capable of extracellular activation through the formation of signaling complexes with the CD8 cell and subsequent internalization and transfection of the tumor-specific CD8 cell clone. The aAPC will consist of a polymeric core and encapsulated siRNA which will be optimized based on transfection efficiency, cytotoxicity, and proliferative capacity, and will be functionalized with he two necessary signals for T cell activation - signal 1 MHC dimer loaded with a tumor antigen and signal 2 anti-CD28 monoclonal antibody. Phase 2 will involve targeted SPRY2 knockdown and the correlation of tumor-specific CD8 cell functionality with SPRY2 levels in vitro. Finally, the third phase will consist of evaluating aAPC-mediated SPRY2 knockdown in an in vivo model of murine colon cancer. If successful, the research will reveal a novel target for improved ACT as well as engineer an innovative platform for monoclonal T cell transfection and stimulation.